Don't break the green diamond with Color Burst. Break it before, as a regular match. Make sure you match red and blue combos that way, that you bring three green diamonds together, after a few moves. Plan your moves!

Don't let the flow of water to the exit before you've charged up your Magic Orb completely.

Second board: Use Color Burst immediately, on the green diamond, which is on the exit. Afterwards, match biggest combos possible, so that you charge up Magic Orb again quickly, without letting the water to the exit ground block. Use the Magic Orb on the blue diamond. Then you shouldn't proceed to the next board immediately. Try to match some more big combos after you've destroyed the bottom two diamonds, and charge up the Magic Orb, at least partially. Then you can proceed. You'll need another Color Burst for the next board, and it's much easier to charge it up on second board, not the third one.

Third board: Use your Color Burst on red diamonds. If you've accomplished this, you should spend just a few more moves to get the flow of water to the firefly. Good luck!